by Susan Page, USA TODAY

by Susan Page, USA TODAY

WASHINGTON -- The GOP platform leaves no doubt about its absolute opposition to same-sex marriage, but Republican National Chairman Reince Priebus says the party needs to welcome those with other views on a combustible issue that will be considered by the Supreme Court today.

"We do have a platform, and we adhere to that platform," Priebus said in an interview Monday on USA TODAY's Capital Download video series. "But it doesn't mean that we divide and subtract people from our party" who support the right of gay men and lesbians to marry.

"I don't believe we need to act like Old Testament heretics," he said, saying Republicans "have to strike a balance between principle and grace and respect."

The Supreme Court is slated to hear arguments this morning over the constitutionality of Proposition 8, California's ban on same-sex marriage. On Wednesday, the high court will consider a challenge to the federal Defense of Marriage Act, which prohibits the federal government from extending spousal benefits to same-sex couples.

"We believe that marriage, the union of one man and one woman must be upheld as the national standard, a goal to stand for, encourage, and promote through laws governing marriage," declares the GOP platform, adopted last summer. Priebus' conciliatory comments on the issue underscore rapid shifts in public opinion on same-sex marriage, including overwhelming support among young voters.

Ohio Sen. Rob Portman, on Mitt Romney's short list last year as a potential running mate, announced this month he had changed his view to endorse same-sex marriage after learning his son was gay.

A report the RNC issued last week called for the party to change its tone "on certain social issues that are turning off young voters," many of whom see it as "the civil rights issues of our time." Since then, Priebus said he had heard from social conservatives, long a mainstay of Republican ranks, concerned that the party was shifting its stance on the issue.

The stinging 97-page report outlined changes it said the GOP must make to turn around its electoral prospects after losing the popular vote in five of the past six presidential elections. "For the most part, people understand that if you're basically losing for 24 years, something has to happen in our party," Priebus said in the interview at his office at Republican National Committee headquarters.

Priebus is a former chairman of the Wisconsin Republican Party.

"To me, it keeps coming back to demographics," he said, warning the GOP needs to expand its appeal to Latinos, blacks and other minorities or face "a very bleak future." He sees some lessons learned from the Democratic Party, which underwent soul-searching after the 1988 election. Democrats, who had lost five of the previous six presidential elections, then won with a more centrist nominee, Bill Clinton, in 1992.

"Transformational candidates matter," Priebus said.

He also said proposals to change the way Electoral College votes are allocated, including a plan by Republican legislators in Pennsylvania to distribute them proportionally, was "a healthy conversation for states to have." Democrats have decried the Pennsylvania proposal as a partisan scheme.